There's also the little detail that even if you split an asteroid of that size, the resulting debris that did hit the Earth, even if the two big pieces missed, would be enough to wipe us out Cretaceous style. You don't need an asteroid "the size of Texas" to ruin Earth's shiat. A rock the size of Manhattan would do just fine.

TFA:the device would need to be about a billion times stronger than the biggest bomb ever detonated on Earth -- the Soviet Union's 50 megaton hydrogen bomb "Big Ivan" -- in order to save the world the asteroid.

zedster:is there a practical limit to how large we could make a nuke? I understand the limit for mounting it on a rocket, but if you remove that and set out to make a nuclear landmine, how big could we go?

dragonchild:TFA: the device would need to be about a billion times stronger than the biggest bomb ever detonated on Earth -- the Soviet Union's 50 megaton hydrogen bomb "Big Ivan" -- in order to save the world the asteroid.

zedster:is there a practical limit to how large we could make a nuke? I understand the limit for mounting it on a rocket, but if you remove that and set out to make a nuclear landmine, how big could we go?

zedster:is there a practical limit to how large we could make a nuke? I understand the limit for mounting it on a rocket, but if you remove that and set out to make a nuclear landmine, how big could we go?

There are limits to practicality with a two stage weapon design. Not so much inherent in the physics, but in the implementation.

The smaller you can make the secondary, physically, the more even the compression you can get. The longer it is, the more likely you're going to get some funky boundary instability that'll turn your nice symmetric squeeze into some funky Munroe effect fizzle. I'd guess, too, that you'd eventually hit some propagation time limit causing a toothpaste-squeeze failure even with the primary's x-rays doing the illumination of your HDPE.

I dunno, maybe you could make a different design than the ones we use altogether that might work better, but if you need one device to blow up the asteroid that has to be a teraton yield or something, then you've got a lot of design work to do.

erewhon:zedster: is there a practical limit to how large we could make a nuke? I understand the limit for mounting it on a rocket, but if you remove that and set out to make a nuclear landmine, how big could we go?

There are limits to practicality with a two stage weapon design. Not so much inherent in the physics, but in the implementation.

The smaller you can make the secondary, physically, the more even the compression you can get. The longer it is, the more likely you're going to get some funky boundary instability that'll turn your nice symmetric squeeze into some funky Munroe effect fizzle. I'd guess, too, that you'd eventually hit some propagation time limit causing a toothpaste-squeeze failure even with the primary's x-rays doing the illumination of your HDPE.

I dunno, maybe you could make a different design than the ones we use altogether that might work better, but if you need one device to blow up the asteroid that has to be a teraton yield or something, then you've got a lot of design work to do.

(tongue in cheek) it would be easier to just use Proteus on it.

Odds are we'd see it far enough out to launch a mission of some kind. An unmanned Orion could nudge it out of the way quite nicely.

zedster:is there a practical limit to how large we could make a nuke? I understand the limit for mounting it on a rocket, but if you remove that and set out to make a nuclear landmine, how big could we go?

According to wikipedia, no. A true thermonuclear device ... can be infinitely scaled. However, past a certain point, you're just blowing up more air than you are buildings. Since the effects radiate in all three dimensions from the source of the explosion you'll eventually get better bang for your buck by using multiple smaller bombs.

Take for instance, one bomb that results in an explosion the size of a basketball. Even if you place the center of the ball on the ground, you're only affecting a diameter of about twelve inches - most of which is up away from a target. Now if you take the same volume, but seperate it into ping-pong balls, you can spread them over several feet since the height of the explosions are now only an inch or so.

And as a landmine, it's be extremely impractical. It'd only blow up once, and destroy or set off any conventional mines nearby. Instead of an invading force worrying if they're going to drive over a bomb, they know nothing's there now.

dragonchild:TFA: the device would need to be about a billion times stronger than the biggest bomb ever detonated on Earth -- the Soviet Union's 50 megaton hydrogen bomb "Big Ivan" -- in order to save the world the asteroid.

Karac:And as a landmine, it's be extremely impractical. It'd only blow up once, and destroy or set off any conventional mines nearby. Instead of an invading force worrying if they're going to drive over a bomb, they know nothing's there now.

MadAmos:Odds are we'd see it far enough out to launch a mission of some kind. An unmanned Orion could nudge it out of the way quite nicely.

I don't think that's the case. Odds are we wouldn't even see it until it was far too late; asteroids are small and don't reflect much. We'd have to be looking in the right place at the right time. We didn't know about our most recent near-misses until afterwards.

I think they misinterpreted a number of things from the movie that would be contributors:

1) The "size of Texas" comment was likely not a diameter measurement, but a rough reference of mass comparison to help the President interpret the 97.6 billion (likely tons) comment coming from the engineer. This study took the largest possible measurement, called it a diameter, and multiplied it into a volume. Not a charitable interpretation.

2) Composition and density of the asteroid will change the energy needed by multiples of a thousand very easily. Granite vs. iron vs. whatever. Remember, they had to punch through in the bad landing zone had a large amount of compressed iron to get through before they got to a softer rock during the drill. They might have been drilling down to a very soft and easily fractured rock. Thus more energy could have gone into separating the hemispheres.

3) The point of the "drill point" was to rest on a fault line, meaning there may have been a very small amount of rock that needed to split to break the halves apart. Most of the split may be been from the natural irregularities running through the asteroid. They chose that side of the rock to minimize the amount of rock that needed to be fractured to split the asteroid. The explosion at the end confirms this idea.

4) The force exerted would be dependent on how confined the device was. This is alluded to several timed in the film (the firecracker analogy).

no plan to deal with asteroids would involve trying to blow up the asteroid by drilling a bomb or bombs into an asteroid. Deflection is the best way to deal with asteroids. Though the idea of a gravity probe was interesting. An object launched from Earth with enough mass to pull the asteroid with it into deep space.

1) The "size of Texas" comment was likely not a diameter measurement, but a rough reference of mass to help the President interpret the 97.6 billion (likely tons) comment from the engineer. This study took the largest possible measurement, called it a diameter, and multiplied it into a volume. Not a charitable interpretation.

2) Composition and density of the asteroid will change the energy needed by multiples of a thousand. Granite vs. iron vs. whatever. Remember, they had to punch through compressed iron on the "bad" landing zone before they got to a softer rock. They might have been drilling down to a very soft and easily fractured material. Thus more energy could have gone into separating the hemispheres instead of cracking it.

3) The purpose of the chosen depth and location for drilling was to reach a fault line, meaning there may have been only a very small amount of rock to split to break asteroid apart. Most of the "split" may be been from the natural fault line running through the asteroid. The explosion confirms this idea at the end of the movie.

4) The force exerted would be dependent on how confined the device was. This is alluded to several times in the film (the firecracker analogy).

zedster:is there a practical limit to how large we could make a nuke? I understand the limit for mounting it on a rocket, but if you remove that and set out to make a nuclear landmine, how big could we go?

no limit. hydrogen bombs increase their output by essentially just dumping on more H to the fire.

imfallen_angel:Because People in power are Stupid: What if we hit it earlier, like way earlier than it's orbital pass- couldn't we nudge it into a different course?

That's always been my take on it.

Moving it by just a tiny degree from far enough, and by the time it get's close, it'll miss by quite a bit.

If anything, the last thing we'd want is a broken to million of pieces cloud of mini asteroids hitting the planet.

We just need to ensure that it's gonna miss the moon and not end up in some sort of gravity pulled boomerang trajectory.

It anything, don't send a bomb, send a very powerful engine to push it into such an angle.

Those are the the questions I wish they had focused on:

Assuming the mass is x, and the speed towards the earth is y, how much thrust would you have to apply (and at what point) to move the trajectory to a safe range? How big would the "engine" need to be? How would you "catch up" to the asteroid to place the engine?

while a gravity probe is an interesting concept what mass would it take to actually deflect an asteroid. I would expect at least 10% of the asteroid's mass would be enough to deflect it but i don't really know about that part. The thing there though is if we can build a rocket that can launch such a mass into orbit then the same rocket can be attached to the asteroid to deflect it with.

There is a final question that isn't answered. What effect would a nuke have in a vacuum? Any nuclear explosion we've ever seen has happened inside an atmosphere with several tons of air to act as a reaction mass if you will. Does the presence of this gas effect the yield of the bomb?

Assuming the mass is x, and the speed towards the earth is y, how much thrust would you have to apply (and at what point) to move the trajectory to a safe range? How big would the "engine" need to be? How would you "catch up" to the asteroid to place the engine?

I know...

What about some sort of solar sail?

What about a series of detonations so to create a series of multiple waves that would cause a growing increase by each blast?

What about having a projected blast, using a rocket with a shield to push the wave so to increase it's strength by means of a parabolic effect?

Without an atmosphere, the blast of a bomb would be far from the same effectiveness as on a planet, which is why I consider that something that would provide thrust would be more effective.

relcec:zedster: is there a practical limit to how large we could make a nuke? I understand the limit for mounting it on a rocket, but if you remove that and set out to make a nuclear landmine, how big could we go?

no limit. hydrogen bombs increase their output by essentially just dumping on more H to the fire.

It's not that simple. Scaling up presents issues that are non-trivial. Mostly around instability in high compressions and timing.

Problem with that is, you have to make the antimatter, then store it , then put it in a bomb. All on earth ... also fark that idea.

Hitting it with a few 100 MT bombs in the same spot over a period of time might heat the surface enough to deflect it's trajectory. Like someone else said a couple degree course change far enough out would be plenty.

Sure, now all we need to do is wait for a good special on antimatter at Home Depot.

Go ask CERN, it is a by product of particle accelerators. Unless you snag it in a magnetic field it'll just pop back out of existence but they do have rather strong magnets there. They can probably supply you with the 'magnetic bottles' needed to transport it back home as well.

We've already ferried anti-particles around on airplanes, it's a faff and I'm sure the expensive 'bottle' was guarded less some baggage handler steal it but beyond that not a problem.

I didn't say getting your hands on a stable vial of AM would be cheap now did I?

Energy before atmospheric entry: 2.12 x 1031 Joules = 5.07 x 1015 MegaTons TNTThe average interval between impacts of this size is longer than the Earth's age.Such impacts could only occur during the accumulation of the Earth, between 4.5 and 4 billion years ago.Major Global Changes:

The Earth is not strongly disturbed by the impact and loses negligible mass.3.56 percent of the Earth is meltedThe impact does not make a noticeable change in the tilt of Earth's axis (Depending on the direction and location of impact, the collision may cause a change in the length of the day of up to 6 minutes.The impact does not shift the Earth's orbit noticeably.

Sure, now all we need to do is wait for a good special on antimatter at Home Depot.

Go ask CERN, it is a by product of particle accelerators. Unless you snag it in a magnetic field it'll just pop back out of existence but they do have rather strong magnets there. They can probably supply you with the 'magnetic bottles' needed to transport it back home as well.

We've already ferried anti-particles around on airplanes, it's a faff and I'm sure the expensive 'bottle' was guarded less some baggage handler steal it but beyond that not a problem.

I didn't say getting your hands on a stable vial of AM would be cheap now did I?

Having more than a handful of particles, now, that's the trick. The more you have, the stronger the bottle has to be exponentially. They're usually charged - mostly CERN makes positrons - and the more you have the more they repel each other. It is a problem.

erewhon:relcec: zedster: is there a practical limit to how large we could make a nuke? I understand the limit for mounting it on a rocket, but if you remove that and set out to make a nuclear landmine, how big could we go?

no limit. hydrogen bombs increase their output by essentially just dumping on more H to the fire.

It's not that simple. Scaling up presents issues that are non-trivial. Mostly around instability in high compressions and timing.